Points, Lines and Planes Geometry Farris 2015

I can use the undefined geometric terms (point, line, plane, ray) to define angles and line segments.

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TermNameDiagram Point – names a location and has no size. It is represented by a dot. A capital letter point P  P Line – a straight path that has no thickness and extends forever. A lowercase letter or two points on the line Line l XY or YX   X Y Plane – a flat surface that has no thickness and extends forever. A script capital letter or three points not on a line Plane R or plane ABC AA BB CC R

DefinitionNameDiagram Segment – or line segment, the part of a line consisting of two points and all points between them. The two endpoints AB or BA   A B Endpoint – a point at one end of a segment or the starting oint of a ray. A capital letter C and D   C D

DefinitionNameDiagram Ray – a part of a line that starts at an endpoint and extends forever in one direction. Its endpoint and any other point on the ray RS    R S   R S Opposite Rays – are two rays that have a common endpoint and form a line. The common endpoint and any other point on each ray EF and EG   F E G

Postulates A statement that is accepted as true without proof. Postulates about points, line, and planes help describe geometric properties.

Postulates – Points, Lines, and Planes Through any two points there is exactly one line Through any three noncollinear points there is exactly one plane containing them If two points lie in a plane, then the line containing those points lies in the plane.       

1-1-4 If two lines intersect, then they intersect in exactly one point If two planes intersect, then they intersect in exactly one line. Postulates – Lines, and Planes

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